[POWERPC] spufs: dont try to access SPE channel 1 count

The save/restore sequence for SPE contexts currently attempts to save
and restore the channel count for SPE channel 1 (the SPU_WriteEventMask
channel.  But the CBE architecture (section 9.11.2) clearly states
that this channel does not have an associated count.  Hardware simply
ignores the attempt to write this count, but the simulator generates
a warning message.

WARNING: 279721590: SPE7: Attempt to write channel count for CH 1 with
no associated count is ignored.

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>